Nanboku-cho period

The Nanboku-cho period, also known as the Northern and Southern Courts Period, was a period of Japanese history from 1334 to 1392 that saw the Ashikaga clan vie for power against the Hojo of the Kamakura Shogunate and Emperor Go-Daigo himself. Ashikaga Takauji's victory at the Battle of Minatogawa led to the downfall of the Kamakura and the rise of the Ashikaga Shogunate, but Go-Daigo set up his own imperial court to rival the court in Kyoto, with the southern court being based in Yoshino. The period would end in 1392 with the fall of the Southern Court forces, but the Southern Court has been acknowledged as the legitimate rulers of Japan at the time, while some Southern Court descendants challenge the Northern Court-descended emperors of Japan for legitimacy.

Background
In 1192, Minamoto Yoritomo founded the Kamakura Shogunate, which served as a regency over the imperial house. The first three shoguns were Minamoto, the next two Fujiwara, and the rest of many houses, but from 1199 to 1256 the Hojo held the title of shikken, military dictator of Japan. The Hojo influenced the decisions of the shogun and therefore the Emperor as well, and Emperor Go-Daigo tired of the meddling of the shoguns and shikkens in his affairs. In 1331, he began a rebellion against the Kamakura Shogunate and brought the downfall of the Hojo with the capture of Kamakura in 1333. However, the ambitious Ashikaga Takauji made a bid for power, leading his armies towards Kyoto. In 1336, the imperial forces were crushed at the Battle of Minatogawa, and the Ashikaga clan founded the Ashikaga Shogunate to rule Japan instead of either the Hojo or the emperors. In response, Go-Daigo founded the Southern Court in Yoshino in opposition to the Northern Court of Kyoto, and the Nanboku-cho period began.

History
The battle of Minatogawa led to the outbreak of a civil war in Japan between the Ashikaga, Kanto Kubo, and their allies and the Southern Court and its allies. The war was fought mostly in central Japan at the time, with the Northern and Southern Courts engaging in battles that saw Kyoto change hands quite a few times; however, the situation changed in the Kanno disturbance of 1350-51, which saw Ashikaga Takauji's older brother Ashikaga Tadayoshi defect to Go-Murakami's cause and lead his forces in an Ashikaga civil war against Takauji.